Hard impregnating finish?

[Ralph E Burns]

Hello SawMillers –

I’m seeking to improve my meager woodworking skills and looking for some pointers. To be honest, my project is to build cabinets for a Sprinter camper van that I’m outfitting – but I won’t be happy with the usual crap job. I’m seeking to honor the approach of my late father, who did meticulous work. I foresee learning ply bending in my future.

Right now I’ve got a finishing question. Probably my first mistake, I have large sheets of Baltic birch ply for flooring that I’ve cut tight tongue & groove joints but have not proceeded further. To combat the softness of the birch, I’d like to impregnate the top ply with some clear hardening polymer / resin, but don’t know the best product to use.

I tried System Three Clear Coat, but it was too viscous to penetrate any notable depth. I might buck the instructions and thin with acetone and try again.
www.systemthree.com/products/clear-coat-low-viscosity-epoxy-sealer (http://www.systemthree.com/products/clear-coat-low-viscosity-epoxy-sealer)

For less fussy projects I’ve used wipe-on Poly and it’s a contender because it is pretty thin. I’m curious about two part and catalytic finishes and if these might be hard.

Likely making this more difficult, I am going to stain the wood grey, and the stain I like is General Finishes Grey oil-based Gel Stain. The thick oil stain gives a differential color with the wood grain, while water based-stains make for a more homogenous and blah flat color. But the oil stain will block wood pores more, making my resin penetration goal harder to achieve.
generalfinishes.com/wood-finishes-retail/oil-based-wood-stains-sealers/oil-based-gel-stains (https://generalfinishes.com/wood-finishes-retail/oil-based-wood-stains-sealers/oil-based-gel-stains)

Here’s what I *think* is the order of operations. Please steer me in the right direction!


Cut tongue & groove joints
Sand joints perfectly flush to a grit #? that is good for staining and penetrating
Stain the tops of the pieces and let dry for plenty of time
Glue the tongue & groove joints. So far am intending to use System Three T-88 epoxy. Will test to make sure any squeeze-out doesn’t remove the stain. www.systemthree.com/products/t-88-structural-epoxy-adhesive (https://www.systemthree.com/products/t-88-structural-epoxy-adhesive)
Add unknown clear impregnating coat on top. No sanding or I’ll remove stain, right?
Keep adding coats of who-knows-what clear coat. At some point there will be enough buildup that I can sand without breaking thru to the stained wood.
Maybe the topcoat should be traditional wood floor oil-based polyurethane, like Bona?


What products could I test for the impregnation???

Be gentle… I’m kinda a beginner. What I learn on this flooring project I’ll apply to fussier cabinet projects in the near future… I’ve got *ideas*!

[Jamie Buxton]

Finishes appliied outside a vacuum chamber don’t so much impregnate as they make a coat on top on the wood. And wood finishes, at the heart of it, are basically plastic, so that’s the hardness you get.

[John TenEyck]

I would use a commercial vinyl flooring product in a camper van. Much less work; much better durability than anything you can make yourself; probably for less money, too.

John

[Edward Dyas]

You may be going about it wrong. Cabinets in a camper even though they may not get rained on would be considered an exterior product. It would be exposed to much more heat and humidity than cabinets in a kitchen so the wood is going to expand and contract more. If you use a really hard finish it won't be able to deal with the wood movement and likely start cracking and lifting. You would be better off using a marine grade spar varnish even though it is softer. It needs to be elastic enough to deal with the wood movement and therefore it's a softer finish.

[Ralph E Burns]

Cabinets in a camper... ..would be exposed to much more heat and humidity than cabinets in a kitchen so the wood is going to expand and contract more... ...You would be better off using a marine grade spar varnish even though it is softer...


Edward - sounds like sage advice! Do you have a favorite marine spar varnish? I'm headed to a couple finishes supply stores in the next day or two and will seek something that can take the big environment swings. I did pick up a some finishing books from the library but will go back and try to learn from boat builders' experience (a.k.a. teak & holly finish)!

[Edward Dyas]

Edward - sounds like sage advice! Do you have a favorite marine spar varnish? I'm headed to a couple finishes supply stores in the next day or two and will seek something that can take the big environment swings. I did pick up a some finishing books from the library but will go back and try to learn from boat builders' experience!The best spar varnish on the market is Epifanes. It's formulated to use to use on the deck of a boat. It's available at places that sell boat supplies and a little pricy. A cheaper spar and easier to locate that I could recommend is Cabot spar varnish. The only one I would really stay away from is Helmsman spar urethane. It won't last very long at all.

[Ralph E Burns]

The best spar varnish on the market is Epifanes...

I phoned Epifanes and spoke to tech support (Jason S.). He stressed that because my wood is plywood, it is already dimensionally stable due to the glued layers. As such, he recommended Epifanes 2-part polyurethane for durability over their clear varnish.

From our conversation, I heard:
(1) Use 2-part PU: https://www.epifanes.com/page/clear-gloss-or-satin First coats gloss, top coats satin.
(2) Thin first coat 25%: https://www.epifanes.com/product/00/PUTB.1000/Polyurethane-Brush-Thinner-1000-ml
(3) Thin second coat 15%.
- Don’t thin after the 2nd coat?
- Apply coats every 24 hours for chemical bonding without sanding.
- After several (4-6) coats, cure for > 48 hours and sand flat before applying satin topcoat. Not sure what grit, but the word was don't go crazy.
(4) Roller-apply: http://www.epifanes.com/product/00/RCM/Roller-Cover-Moltopren

I could use the System 3 epoxy sealer already bought on the underside.

I'm interested in learning to spray when it comes to applying the cabinet finishes; perhaps a large airbrush could be reasonably suited to my small projects.

[Mark Daily]

To combat the softness of the birch, I’d like to impregnate the top ply...”

Who wants a pregnant piece of wood, lol?

[Edward Dyas]

That polyurethane is recommended for an interior finish. When a product says for interior use it generally means a place that is climate controlled. I think the application you are planning calls for an exterior finish because of the temperature and humidity swings.

If you plan to use a roller you might better try it on scrap first. Some of those foam rollers put a lot of air bubbles in the finish. I've quit trying to roll varnish for that reason. I either brush it or spray it.

[Ralph E Burns]

Hard wood impregnates!

[Ralph E Burns]

That polyurethane is recommended for an interior finish. When a product says for interior use it generally means a place that is climate controlled. I think the application you are planning calls for an exterior finish because of the temperature and humidity swings.

If you plan to use a roller you might better try it on scrap first. Some of those foam rollers put a lot of air bubbles in the finish. I've quit trying to roll varnish for that reason. I either brush it or spray it.

Thanks again @Edward !

I did tell Jason at Epifanes that the temperature swing would be -10F to +150F. Sounds like his recommendation is because it's plywood flooring. He recommends this finish for longevity on boat cabin soles - the teak & holly flooring. So I will try some... since I have to mail-order the question is do I just buy enough to sample or enough for the whole job (it's spendy!).

I will buy the Epifanes-brand foam rollers... but am interested in spraying. What I could do without investing huge bucks? I have a 2-gallon air compressor.... did spray PU paints before using an artist's airbrush... wonder if I could do that since the jobs are small (first job = 56 sq feet).

From the Epifanes guy:
"Brushing/rolling: You can thin a little if needed but less than 10%
Standard HVLP gun is best 1.4- 1.8 tip at 15-20% Spray thinner
Sand with 320 for best finish"

He did stress that thinning embrittles the finish.

[Edward Dyas]

The airbrush would be too small. You could use a cheap harbor freight sprayer to spray the finish. They do well for wood finishes. I use the model #69704 which I get for about twenty bucks with one of their 20% off coupons. With that size compressor you couldn't spray very much at one time before the pressure would drop too low. If you could spray the doors separately it would help a lot. It's just when you spray an area you can't stop, you have to keep a wet edge on the finish or it will show a line where you stop and start.

[Mark Daily]

Hard wood impregnates!

Funny- LOL!

[Ralph E Burns]

The 2017 Fine Woodworking book "Finishing Wood" reviewed some and Fuji Mini-Mite 3 and Apollo Eco-3 received high marks; both are around $680.

I might ask Fuji about this $440 one: https://www.amazon.com/Fuji-2203G-Semi-PRO-Gravity-System/dp/B00D4NPPQY/

[Edward Dyas]

Those turbine type sprayers are alright for spraying walls with latex paint but have a bad reputation for spraying woodwork. For that amount of money you should be able to get a descent size compressor and a regular sprayer. The turbine sprayers tend to splatter the paint rather than spraying a fine mist like you need for woodwork and furniture.

[Ralph E Burns]

Thinking that I should hold onto my pocketbook until after I try rolling and brushing this 2-part Epifanes... since a sprayer will blow away some of that spendy finish! If I do get something I'll probably not get Fuji's base model, but a 3- or 4-stage unit.

For brushing I'd have better application success thinning the top coats, but the Epifanes guy said not to. Makes the finish brittle.

[Edward Dyas]

You would think you use more finish spraying because of the overspray but brushing the finish you tend to apply it thicker so brushing uses about the same amount or less finish than spraying.

Any varnish you shouldn't thin it more than 10%. If you over thin a varnish it can screw with the sheen of the finish, making it duller than it was intended. If you end up brushing the finish use as soft a brush as you can find and apply the varnish as thin as you can with as few strokes as possible. They more you brush a varnish the more the brush marks will show. If it's still warm where you are you can add some flood penetrol to the finish. It will slow the drying time down to minimize brush marks. The brush makes grooves in the finish and needs to flow together before it sets up.

[Tom Hyde]

Unless I missed it, I'm surprised no one recommended a dewaxed shellac (like Zinsser SealCoat) as an initial seal coat prior to other finishes? I'm no expert, and I don't know, but I've found the "fuzzies" from baltic birch to drive me a bit nuts unless I seal coat prior to final finish. Perhaps it's unnecessary. Interested for myself.

[Ralph E Burns]

... a dewaxed shellac (like Zinsser SealCoat) .

One more thing for me to learn about! I'm curious how Zinsser SealCoat is advertised as a pre-stain conditioner (https://www.rustoleum.com/en/product-catalog/consumer-brands/zinsser/interior-wood-finishes/sealcoat-universal-sanding-sealer) for softwoods. Right now my baltic ply has been random-sanded with 240 grit and GF gel stain applied. Think I worked too slow with the gel stain, live and learn.

Yesterday the 2-part Epifanes Polyurethanes (https://www.epifanes.com/product/00/PUCG.750/Polyurethane-Clear-Gloss-750-gr) arrived. Spendy!
Tomorrow a Fuji sprayer (https://www.fujispray.com/mini-mite) arrives! I bought 4-stage for a little more pressure and less thinning.
The garage will get completely emptied this weekend and squeaky-cleaned for makeshift paint booth, and practice will begin!

There are no fuzzies tho, and methinks that I'll have to put down several coats of gloss poly at 24-hr intervals before a hard cure and flat sand and final satin coats.

[Ralph E Burns]

P.S. It all worked out great! There was a learning curve, and a bug dancing on it, so it ended up getting many coats of Epifanes 2-part polyurethane.
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